Electromagnet for rail fissure detectors



July 8, 1952 c. w. MCKEE ETAL ELECTROMAGNET FOR RAIL FISSURE DETECTORS 4' Sheets-Sheet 1 Filed May 20, 1947 y 1 5 c. w. MCKEE ETAL 2,602,840

ELECTROMAGNEIT FOR RAIL FISSURE DETECTORS Filed May 20, 1947 4 Sheets-=Sheet 2 6, 2 V EN TORS.

f i$$ zy/Y'wee July 8, 1952 c. w. MCKEE T 'AL 2,602,840

ELECTROMAGNET FOR RAIL FISSURE DETECTORS Filed May 20, 1947 4'Shee cs-Sheet :5

y 1952 c. w. MCKEE ET AL ELECTROMAGNET FOR RAIL FISSURE DETECTORS 4 Sheets-Sheet 4 Filed May 20, 1947 fil ' mmvrozes azasleriyfii lfee, BYEzc/zczrd W M 566,

j I I Patented July 8, 1952' UNITED STATES PATENT OFFICE ELECTROMAGNET FOR RAIL FISSURE DETECTORS Chester W. McKee and Richard W. McKee, Chicago,' Ill, assignors, by mesne assignments, to

Teledetector, Inc., a corporation of Delaware Application May 20, 1947, Serial No. 749,166

15 Claims. 1

This invention relates to an electromagnet for a rail fissure detector and is a continuation in part'of applicants co-pending application, Serial Number 628,146, filed. November 13, 1945. This co-pending application disclosed a three-pole magnet while the present application discloses two three-pole magnets anda five-pole magnet. All claims to magnets as such will be presented in this case.

The general. object of all rail fissure detecting apparatus is to distinguish fissures from harmless fl'aws such as burns during the performance of the exploratory step. One method of distinguishing was disclosed. inthe Frickey andYMcKee Patent No. 2,338,683, wherein an aircore pickup coil having a length along: the rail of less than the length of the residual; flux field above that portion of a rail ball containing. a transverse fissure, will give for album a signal of longer time duration than that for a fissure. As a matter of practice, this method of distinguishing burns from fissures during the exploratory'step:requires a concentration of 'attentionon the screen of the recording cathode ray'tube that tiresan operator. Moreover, the-tube-persiste'ncy islimited'to under four seconds and the operator is never certain as tohisconclusion. a I

With the development of the't'e'stingl of a trailing, sustained field by the present applicants as di'sclosd in' the-above mentioned co-pending application, also employing the small; aircore coil,

applicants noted that the; harmless flaws gave such weak potential signals: in. the pickup that they could be distinguished from fissure signals by means or intensity alone. Inshort, by means of a suppressor, the signals from a burn spot it is increased,"the greater thefdifferehcegbetween a potential signal from harmless flaw, suchias a burn;' andaipotnti ignalg-rrornai fissure l Applicant's are preps. ed toloffer anexplananumeral l0 generally identifies a rail having. a ball 12,- a web 14, and a base 16, and the numeral 18 identifies a vertically disposed electro-magnet having north and south poles. This magnet has moved from the point 20 to the position shown in a selected period of time. Around this magnet are indicated lines of force 221', creating what applicants refer to as a trailing sustained field 24 and a leading sustained field 26. The numerals 2'8 and 30 identify two internal. fissures in the rail ball which are assumed to be ofidentical size, and the numerals 32 and 34 identify two like sized burnsv having identical hardened shells in the rail ball. Thearrow 36 is at the point distant from the magnet ['8 where a magnetometer of the type described in the copending application (Experiment 2 on pages f-ll thereof) ceases to show any difference between the strength of the field around the rail ball due to energization of the magnet [8) That part of the rail to the left of the point 36 may be 0011- sidered as residually magnetized, and that part to the right as being in the sustained field 24.

Applicants have indicated by dotted lines-in the fields 38 and 40 their concept of the direction of flux flow in residual fields around those portions of a rail containing a fissure and a burn spot respectively. In both residual fields, the concept is that the flux is parallel to the length of the rail and when these fields aretra'versed by either the short air core coilof the applicants or the multiple iron coreplckups of the A. AsR anondiscriminatory signal will be producedii the potential signals are functioning'a pen unit. If applicants" air core c'oil is hooked to anamplifier connected to the plates ofa cathode ray tube, the differences in" time duration of signals from a fissure and a burn will be observable, and there will also be differencesin intensity. However, the intensity of alp'otent-ialsignal produced by a residual flux field modified by a small fissure, i. e. twenty per cent, is approximately the same as the intensity from a residual flux' fieldr around many burns, and it follows thatone cannot'adjust the amplifier to suppress signals oithis intensity without suppressing :p'otential, signals from small fissures-.4 g a In testing theutrailingi sustaine'd field, the 'situation appearstdbe different. t Figure Z i-san enlargementof the rightten'dlo -;Efig-nre 1 showing the rail ball hi, the magnet, t8?arid ithetrailing =tlo'n forthis t'this time; lthpugn ithey wereinot prepared to do #soi atiithe of filing the; co:- pending application; i Referrin to Figure" 1, the

lines in air aroundabarl magnet, thedot-rdash lines numbering. onlyv two; namely 42 and- 'for illustrative purposes" indicate the position "of the flux in the trailing field 24, assuming that the rail 12 is not in the field. Assume now that these lines of force such as 42 and 44 are intersected by a line 46 which is coincident with the crown of a rail ball when the latter is placed in proper position with respect to the magnet It. It is not necessary to demonstrate the fact that the angle a is equal'to the angle b, and that a flux responsive means moved along the line 46 at a constant rate of speed (and at a contant distance from the magnet l8) will develop no voltage.

When a rail [2 is placed in the position shown in Figure 2, this statementwill for all practical purposes continue to be true. The rail being much more permeable than air will cause the flux to flow along lines, such as 48, 50 and 52, and this will have the effect of producing angles such as C and D with the crown of the rail, which is parallel to the movement of the pick-up. The absence of a more permeable path adjacent the north pole of the magnet l8 will tend to permit the lines of fiux to follow the path which they assume when the magnet is completely surrounded by air. It may be that the angles C and D are not quite equal, that as a matter of fact, the angle becomes greater, the greater the distance from the magnet 18. However, the difference will not be great, and most importantly, applicants pickup coil is short as indicated by the two sides 54 and 56 of a coil generally identified by the numeral 58. For all practical purposes, therefore, the coil is traversing a field in which the angle between the lines of force and its di- 'rection of movement is constant when the rail possesses perfect contour and a perfect cross section.

Figure 3 is an enlargement of the area defined by the rectangle 60 in Figure 2, 38 being the fissure in the rail-ball I2, and 34 being the burn. The lines of force 48 to 52, as well as many other-lines of force are indicated. When the lines of force through the burn 34 pass from the rail ball into the air, their direction is not changed. This followsfrom the concept of magnetism that there is no angle of refraction when fiux passes from a material having one density lpermeability) into a material having another density, as in the case of light passing from air into glass. I-tis true that the burn will slightly change the angle of the fiux due to its providing a shorter path or due to the alteration of the grain structure of the steel at the surface, as by hardening, but the center of the flux circuit, i.- e., its motivating force, is the magnet l8. In the magnet circuit, the effect of the burn is negligible because the lines of force are governed by their relationship to the field as a whole which tends to resist modification by the burn. This should be contrasted with the effect of the burn spot on a residual magnetic field where the steel around the burn substitutes itself for the magnet l8 as the main element of the fiux circuit. In the latter case, the burn, being on the surface of the rail "ball, immediately adjacent to the pathof the fiuX responsive means, has an advantage over the internal fissure in creating a fiux field showing changes of direction and intensity which will produce-avoltage in the pickup circuit. Referring now to the effect of an internal transverse fissureon the fiux field 24, and again referring. to Figure. 3, the fissure 313 is a comparatively'small fissure. It extends perhaps one-third of the height of the rail ball and if it extends one-half the'width of the rail ball, it will occupy one-sixth of the crosssectional area of the rail ball, or but slightly more than a 15% fissure. This fissure will substantially change both the angle of the flux in the field 24 immediately adjacent to the top of the rail ball and will change the concentration of flux per unit area. The fissure 30 is a separation of the metal inside the'rail ball so as to create two faces, 62 and 64, which are very close together, but which, when the rail is magnetized, undoubtedly produce opposite polarity in the faces 62 and 64. What is more important, across the fissure, the path for flux is a vacuum or air and is much less permeable to the flux than is the rail ball itself. The result is that lines of force, such as 66 and 58, will tend to follow the paths, such as 10 and I2 and in the adjustment, these lines of fiux will be squeezed into a smaller area indicated by the square 14. Moreover and importantly, this area 14 will be followed by an area 16 having a reduced number of lines of flux because of the comparatively dead space, dead from the standpoint of flux density, 18, immediately behind the fissure 30. When a pick-up such as 58 successively passes through these zones 16 and 14, it will refiecttwo voltage producing factors, the abrupt changes in flux angularity with respect to its course, and the changes in the flux density.

From the foregoing it seems that the greater the volume of flux having a single polarity that can be pushed out from the pole of the trailing magnet, and the closer that the flux responsive means can be mounted to that magnet, the more marked will be the difference between a potential signal created by an internal defect in the rail ball and the potential signal created by a surface defect such as burns, shells or fiow.

The general object of this invention is, therefore, to increase the intensity of the trailing sustained field 24.

The specific object of this invention is to attain the general object without increasing the E. M. F. required to operate a magnet. From a study of ordinary college textbooks on magnetization, one would conclude that this cannot be done. In such discussionsthe time element is completely ignored. Thus, in Lord Kenyons careful establishmentof theaccepted hysteresis curve, the values are obtained for any given magnetizing force by applying. the magnetizing force until no further change in the fiux field in the metal is perceived. Presumably, if a given rail can be saturatedt-with a magnetizing force represented by X in fourjseconds, a magnetizing force of 2X might requireonlythree seconds. It would seem that the-time required would vary inversely and probably proportionately with the magnetic force applied, At any event, the experiments of applicant, Chester W. McKee, and his associate, Royal Frickey, showed many years ago that the strength of the residual magnetic field varied indirectly; with the rate of speed at which a magnet movedalongthe top of the rail. These' same observations-have been made in studying the strength ofthe-trailing sustained field and applicant hIGiIly'PlOVidGS a magnet which' has five poles instead of, three for the purpose of lengthening the timein which the magnetic. force is. applied to the rail, even though for all practical purposes onlythefield created by the trailing magnetic. pole is being tested.

A feature oftheginvention is the fixed relationship of, the.magnet;;p01e,Diecesor shoes to 5. swingingmotion to the molecules which assists the trailing pole piece in giving them a final set in the trailing sustained field.

The invention is disclosed in three embodiments in four sheets of drawing. The first embodiment is shown in Figs. 4 and 5 which are reproductions of Figs. 9 and 10 of co-pending application Serial No. 628,146. The second embodiment is disclosed in Figs. 6, '7 and 8 which show a five-pole magnet in side elevation, plan view and end elevation respectively. Fig. 9 is a view of the magnet case. The third embodiment, which is the preferred form, is disclosed in Figs. 10, 11 and 12, being a side elevation. a bottom view and an end view respectively.

The first embodiment The description of the first embodiment of the invention will be taken directly from the copending application as follows:

Referring now to Figures 4 and 5, 344 and 346 are a pair of aluminum bars maintained in spaced relationship by means of four sets of independently rotatable, roller bearing wheels such as 343 and 350, with necessary shafts and locking means. Vertically disposed between said bars 344 and .346 and between two sets of rollers at each end are iron cores 352 and 354. Mounted on the lower end of each is a wedged shaped member 356 and 358 which is of conductive metal,

and which has an elongated horizontal flux transmitting face such as 361 or 363.

The upper ends are joined together by a top bar of iron 360 so that in substance the magnet appears to be an ordinary inverted U-shaped magnet. The two cores 352 and 354 are spaced apart by approximately eleven inches.

Disposed intermediate to core members 352 and 354 is a similar core member 362 of the same cross dimension and same material, excepting that this member has its upper end 364 mounted on a two-inch brass, right parallelogram 366 so that there will be no direct flow of flux through metal from the top bar 360 to the middle core member 362. Attention is also called to the fact 1 that the lower end368 is spaced from the ball 370 of the rail by a much greater distance than are the pole pieces on the two outside core members 352 and 354. In fact, the spacing of the central core member 362 is approximately threeeighthsof an inch while the spacing on the end ductors 134 and 138 which bear the same numhere on the wiring diagram, Figure 4. v

The spacing of the upper member of the inermediate core member 362 from the top bar 366 and the spacingv of its lower end 368from the rail ball are a result of experiment. The experiments were performed with the magnetometer while the magnet was both stationary and moving and itwas found that the spacing described gave the best results. It is appreciated that many factors enter-into the relationship of the parts of this magnet.

v Prominent among theseis themagnets-capacity and-the capacity of the generator, the size of the rail ball that is being tested, and the particular materials used in the magnet and the magnet frame. It is thought however, that the greater spacing of the intermediate core member from the rail ball than the spacing of the two outside core members is important and that the spacing of the upper end of the intermediate core member 362 from the top bar 360 by a non-conductor is important. The reduced conductivity for flux of. the core member 362 may have a tendency to force flux on both sides of the magnet so that there is an increased flow of fiux from the lateral sustained fields through the air to the bar 360 in the central position of which above the core 364 there must be a great complexity of molecular polarity.

fAs actually built, the poles 356 and 358 are north poles and the pole 368 is a south pole. and the leads off the flux responsive pick-up are connected accordingly. It is not material, however, that these poles have this named polarity, for the apparatus would work equally well, it is at present believed, if the two outer poles, 356 and 358, were south poles and the intermediate pole 368 was a north pole, the leads from the pick-up 168 would of course have to be reversed.

This magnet gives the lateral sustained field on either side of the outside pole pieces 356 and 358 mentioned in Experiment 2 in the introductory part of the disclosure. Assuming that the magnet is moved to the right, applicants refer to the sustained field which follows the pole 356 for a distance measurable by the magnetometer up to about six feet as the trailing sustained field.

: Applicants are confident although experiment has not yet been made, that, assuming the same directional movement of the magnet, the pick-up could be mounted in advance of the pole 358 and would find there a sustained field. This is called the leading sustained field. It is not thought that testing in the leading sustained field would be as effective as testing in the residual or trailing sustained field, for the reason that there would not have been the beneficial oscillation of the molecules to negative pre-testing magnetic fields around the rails that there has been when the testing is done in the trailing sustained field.

The second embodiment The second embodiment of the invention is shown in Figures 6, 7 and 8. Referring to Figure 6, 63, 92, '94, 96 and 98 are spaced highly permeable bars of iron held in parallel spaced relationship by means of a non-magnetic headpiece and a pair of aligned base members I02 and :65. Head member I00 is held to each bar, such as 96, by a bolt Hi6 threadedly seated in a tapped hole I68 in the upper end of the bar. The bar 63 is round. A pair of collars, H0 and H2, are mounted on each bar for confining the windings H4 in the position indicated. The parallel supports E62 and E64 are mounted on two types of shoeswhich in turn are mounted on the bottomof the bars 36 to 98.

The "first type of shoes may be called the critical pole shoes, such as H5, H8 and 120, and the second type of shoes may be called the non-- critical pole shoes, such as l22-and I24. 'The critical shoe is that shoe which establishes the polarity in that portion of the rail in which the flux responsive means functions. It follows that where the flux responsive means is positioned in either the trailing or the leading field, theoutside poles of-a multiple pole magnet will be the critical poles.

Examining now critical pole shoe I I6, it is seen to consist of a casting made of high flux permeable material having a downwardly directed wedge-shaped configuration with rounded apex I22. See also Figure 7. This shoe is tapped to form a circular opening I24 in which fits the magnet 60. The two are joined by any suitable means. The shoe I I6, referring to Figure 8, has a width approximating that of the pole of a standard rail I23, namely 3", and as may be seen in Figure 8,'the base members I02 and I04 are fastened to the shoes I I6, I I6 and I20 by a means of bolts, such as I26, which hold the base members I02 and I04 directly to the sides of the shoes.

The non-critical shoes, such as I22 and I24, referring to Figure 6, consist of a segment of a cylinder which is spot faced to form a cylindrical seat I28 in which is mounted the lower end of the magnet 92. They are held in assembled similar relationship by a bolt I30. Each side of the shoe is tapped, as at I32, see Figure 7, to receive a bolt through the adjacent base member I02.

Three sets of wheels support the magnet referring to Figures 6 and 8. Each set of wheels comprises four Wheels such as I34, I36 and I38 which are mounted by some standard bearing assembly on shafts, such as I40 and I42. These shafts I40 and I42 are mounted in fixed axial position in the base members I02 and I04.

The windings on the magnets are all identical, but the windings on magnets 92 and 96 are reversed With respect to the windings on 90, 94 and 98 so that if the windings produce a south pole at the lower end of the magnet 98, 06 will have a north in the same position, 94 a south, 92 a north and 90 a south.

The thought governing the provision of different types of pole pieces such as I I6 and I22 is this. The critical pole shoe will concentrate fiux in the rail beneath the shoe and tend to give the molecules in the rail a more definite set that the non-critical shoe which disperses the flux over a much larger area. The purpose of having reversed poles in alignment is to cause at least a swinging movement of the poles of the molecules in the rail and then the final pole, in this case, I I6, assuming the magnet is moving to the right, will be able to give a more definite set to the molecule poles than is possible if the magnet I I! alone were working upon the molecules. Applicants do not believe that accepted hysteresis curves will be useful in understanding the functioning of this magnet. According to Lord Kenyons hysteresis curve, the amount of residual magnetism in the rail after the pole I20 has passed over it will be exactly the same as the amount in the rail after the pole II8 has passed over it. As mentioned heretofore, this is based on conclusions reached regardless of time. Applicants believe that where the first magnet such as 98 only partially saturates the rail, the reversal by magnet 96 and then the remagnetization by magnet 94 will raise the flux density to a point higher than was raised by the magnet 99. On the reversal of the magnetization when the magnet 92 passes over the rail, the reverse polarization will not be as great, and finally the wedge shaped head I I6 of magnet 90 will give a stronger magnetization to themolecules than either magnet 98 or 94 coulddo.

Theadvantage of having the wheels mounted rigidly in the frame lies in the 'fact that they will carry the magnet over low spots in the rails better than would spring-mounted trucks. On

8 the average, accuratespacing between the poles of the magnet and the top of the rail is better obtained by wheels-mounted in this fashion.

The configuration of the cross section of the wedge head I I6, referring to Figure 6, is parabolic about a center I21 and is believed to provide the best path for flux flowing from a magnet such as 90 into a rail ball having a somewhat rectangular cross section.

In'Figure 9, which is a reproduction of a portion of Figure 5 of the said co-pending application, the numeral I46 identifies a casing which is mounted by end bolts I48 and I50 in seats, referring to Figure 6, I52 and I54, on the opposite ends of the member I00.

The third and preferred embodiment The third and preferred embodiment of the magnet is illustrated-in Figures 10, 11 and 12. This is a three-pole magnet having, however, five energized cores. Referring to Figure 10, the five cores I60, I62, I64, I66 and I68 are suspended from a non-magnetic header I10. The windings on cores I60, I62, I66 and I63 are in the same direction, so that their bottom poles will have a like polarity, in this case north. The core I64 is wound in an opposed direction so that its bottom pole is of an opposite polarity, in this case south. To the bottom of the poles I60 and I62 is fastened a block shoe I12, which referring to Figure 12, has a width substantially approximating that of a rail ball I14 and extends downwardly to a point just above the rail ball. A similar block shoe I16 is attached to the bottoms of the cores I66 and I66. To thebottom of core I64 is fastened a shoe I13 which is a segment of a cylinder and is spaced from the rail ball by a distance reater than the block shoes I12 and I16 and the rail ball. The shoes are held in fixed, assembled relationship by rails I and I82 and are suspended above the rails by pairs of wheels such as I84.

The whole bottom surface of the block shoes such as I12 is of north polarity and testing seems to indicate that this shoe pushes a greater amount of flux into the trailing sustained shoe than does either of the other two embodiments of this invention. Itis' believed that the improved result stem in part from the greater polarization of the trailing shoe or pole piece I12 as compared with shoe I18, in the example shown, shoe I12 having twice the polarization of shoe I18. The problem is to get the best possible, directional magnetism in the rail ball following the trailing shoe I12 and this depends upon the shape of the shoe I12, its proximity to the ball tread, its degree of polarization, and the effect of the preceding magnetized shoes on any directional set in the molecules in the rail before any magnetization; I

The advantages of these multiple-pole magnets residein the constant relative spacings of the poles above the rail and the spacing of the holes from each other,'which is accomplished by the magnets being rigidly fixed on the frame.

- Applicants magnet is not a mere aggregation of magnets. When any one of three magnets disclosed in this application moves over a rail, applicants concept is that the molecules are placed in motion.

which motion is not completely stopped, until the last magnet has passed on over a given portion above the rail ball. This is to be contrasted with earlier magnets used by others including the applicants wherein a single magnet having a north pole adjacent therail is positioned ahead of the power car,a second magnet having its lower pole of south polarity is positioned at the rear of the power car, and a third magnet is positioned on the fissure detector car itself, this last magnet having its north pole directed downwardly. This last-mentioned magnet arrangement does not accomplish the result obtainedby the single magnet having a plurality of poles disclosed herein. Applicants magnets function because they are mounted on a single frame which maintains their bottom pole pieces at the proper relative distances from the rail ball at all times.

In the claims, the pole pieces and magnets are referred to as even numbered and odd numbered. In Figure 4, pole pieces 35B and 358 are odd numbered and 368 even numbered; in Figure 6, pole pieces I I6, H8 and I20 are odd numbered and I22 and I24 are even numbered; and in Figure 10, I12 and H are odd numbered and lit even numbered. l

Having thus disclosed our invention, what claim is:

l. A rail magnet for progressively creating a trailing sustained field in the balls of rails lying in track comprising a frame having a base, means on the frame for movably supporting it at a constant distance above and adjacent to the treads of the rail balls, and a plurality of magnetizable elongated cores mounted in fixed position with one pole of each mounted in a general straight alignment along the frame base, each pole having a polarity opposite to. the polarity of an adjacent pole and being closer to said adjacent pole than to the opposite poleof its own core.

2. A rail magnet for progressively creating a trailing sustained field in theballs of rails lying in track comprising a frame having .a base, means on the frame for movably supporting it at a constant distance above and adjacent to the treads of the rail balls, and a plurality of magnetizable elongated cores mounted on the frame and each having a downwardly directed pole along the frame base, the centers of said poles being equally spaced from each other and in substantial alignment and adjacent poles being closer to each other than to the opposite pole on their own core, the pole pieces on the odd numbered magnets having one polarity and the pole pieces on the even numbered magnets having an opposite polarity.

3. The rail magnet of claim 1 wherein the odd numbered pole pieces are substantially closer to a plane containing the outer surfaces of the supporting means than are the even numbered pole pieces.

4. The rail magnet of claim 1 wherein the pole piece at one end of the line of pole pieces is considered the trailing pole piece and wherein that pole piece is positioned close to a plane containing the outer surfaces of the supporting means and wherein the next adjacent pole piece is positioned at a substantially greater distance inwardly of said plane. I

5. A rail magnet for progressively creating a trailing sustained field in balls of rails lying in track comprising a pair of elongated members spaced by approximately the width of a rail ball, supporting wheels therebetween adapted to ride the ball tread, a plurality of aligned, vertical, magnetizable elongated cores fixedly supported between said members and having their centers equally spaced from each other, the space between adjacent centers being substantially less than the length of the cores, means for giving one polarity to the Odd numbered pole pieces, and

'10 means for giving an opposite polarity to the'even numbered pole pieces.

6. A rail magnetfor progressively energizing the balls of rails lying in track comprising a frame having a base, means on the frame for movably supporting it-above and adjacent'to the treads of the rail balls, three electromagnets having straight cores vertically and-fixedly positioned on said frame with their lower ends-nearthe frame base so as to be adjacent the tread of 'therail ball, said cores being substantially closer together than their lengths, the end cores'having a like polarity at their bases and the middle core having an opposite polarity to its base, and a pole piece on the bottom of one end magnet, said'pole piece having a uniform, downwardly directed blunted, wedge-shaped cross section with the blunt 'edge transverse to a line connecting the pole pieces.

7. The magnet of claim 6 wherein the pole piece on the middle magnet is spaced inwardly of a plane containing the outer surface of thesupporting means by a distance substantially greater than the distance between the pole piece on the end pole and the same plane.

8. The magnet of claim 6 wherein a magnetic conductor joins the upper ends of the two end cores to each other. I 1 I 9. A rail magnet for progressively energizing the balls of railslying in track comprising a frame having a base, means onthe frame for movably supporting it above and adjacent to thetr'eads of the rail balls, five electromagnet'shaving straight cores vertically and fixedly positioned oris'a-i'd frame with their lowerends near the frame base so as to be adjacent the tread of the rail ball", thelovver ends being substantially closer to each other than the length of a core, the odd numbered cores having a like polarity at their bases and the even numbered cores having an opposite polarity at their bases, and a pole piece on the bottom of one end core, said pole piece having a uniform, downwardly-directed parabolic, cross section with the apex transverse to a line connecting the pole pieces.

10. A rail magnet for progressively energizing the balls of rails lying in track comprising a frame having a base, means on the frame for movably supporting it above and adjacent to the treads of the rail balls, five electromagnets having straight cores vertically and fixedly positioned on said frame with their lower ends near the frame base so as to be adjacent the tread of the rail ball, the lower ends being substantially closer to each other than the length of a core, the odd numbered cores having a like polarity at their bases and the even numbered cores having an opposite polarity at their bases, a pole piece on the bottom of one end core, said pole piece having a uniform, downwardly-directed parabolic, cross section with the apex transverse to a line connecting the pole pieces, and a pole piece on the bottom of the next adjacent core, said latter pole piece having a downwardly directed, convex cylindrical surface with its axis at right angles to a line connecting the pole pieces.

11. A rail magnet progressively energizing balls of rails lying in the track comprising a pair of elongated members spaced by approximately the width of a rail ball, supporting wheels therebetween adapted to ride the ball tread, five aligned, vertically disposed, magnetic cores having their lower ends mounted fixedly between said members, said lower ends being substantially closer to each other than the length of a core, the odd numbered cores having one polarity at their lower '11 ends, the even numbered cores having an opposite polarity at their lower ends, and a non-magnetic bar parallel to the elongated members and fastened to the top of each core.

12. A rail magnet for progressively creating a trailing sustained field in the balls of rails lying in track comprising a frame, means on the frame for movably supporting it at a constant distance above and adjacent to the tread of a rail ball, a plurality of magnetizable elongated cores mounted on said frame, and each having a pole lying along a generally straight line for positioning next to the rail, said poles being substantially closer to each adjacent other pole than to its opposite pole on its own core.

13. A magnet for creating a lateral field at one side thereof in a magnetizable object having a flat 'surface comprising a frame, means mounted on the frame and engageable with the fiat magnetizable object for spacing the frame from said object, a plurality of magnetizable elongated cores mounted on said frame and spaced from each other by a distance substantially less than the length of the cores, adjacent cores having both poles of opposite polarity, and the poles of one polarity having a selected surface area and lying in a plane which will be at a selected distance from the plane of the surfaces of the spacing means and the poles of the other polarity being of a substantially different surface area and being at a greater distance from said plane.

14.A rail magnet for progressively energizing the balls of rails lying in track comprising a frame having a base, means on the frame for movably supporting it above and adjacent to the tread of a rail ball, tWo aligned vertically disposed magnetic cores mounted in fixed position along the frame base, electromagnetic windings on each core for giving both core bottoms a like polariza tion, a magnetically conductive shoe mounted across the bottoms of both cores, and a similar vertically disposed magnetic core mounted in alignment with the first two on said frame, and electromagnetic windings for giving the bottom of this core a polarization opposite to that of said shoe.

15. The rail magnet of claim 14 wherein the elongated shoe is positioned closer to the plane containing the outer surfaces of the supporting means than is the third pole piece.

CHESTER. W. McKEE. RICHARD W. McKEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 21,927 Brace et a1 Oct. 21, 1941 1,082,210 Pace Dec. 23, 1913 1,414,522 Morgan May 2, 1922 1,758,104 Folker May 13, 1930 2,098,064 Pfafienberger Nov. 2, 1937 2,218,784 Billstein Oct. 22, 1940 2,252,424 Bigelow Aug. 11, 1941 2,311,715 Thorne Feb. 23, 1943 2,346,582 Insler et al Apr. 11, 1944 2,425,857 Barnes et al. Aug. 19, 1947 FOREIGN PATENTS Number Country Date 575,480 Germany Apr. 28, 1933 

